Fan with Inverted Electric Motor

ABSTRACT

In one embodiment, a fan may include a housing having an inlet opening and an exhaust opening, a support shaft fixed to and positioned within the housing, a motor having a stator fixed on the support shaft, and a rotor rotatably mounted on the support shaft, and an impeller attached to the rotor, whereby energization of the motor causes the rotor to rotate the impeller relative to the support shaft to move ambient air into the housing through the inlet opening and out the exhaust opening.

FIELD

The present disclosure relates to fans, and more particularly, to fans powered by electric motors.

BACKGROUND

Fans powered by electric motors are widely used and have many applications. For example, a centrifugal fan, also known as a blower or a squirrel cage fan, is the most common type of fan used in the heating, ventilating and air conditioning (HVAC) industry. Centrifugal fans are less expensive than axial fans and are simpler in construction. A typical HVAC application may utilize a centrifugal fan as a blower for a ventilation system in a building. Because of their compact nature in relation to air moving capabilities, centrifugal fans also may be used in the automotive and locomotive industries. In one such application, a centrifugal fan or fans may be used to blow heated or cooled air into the passenger cabin of an automobile or the operator cabin of a locomotive engine.

A centrifugal fan typically includes a housing in which an impeller or fan wheel is rotatably mounted. The impeller is generally cylindrical in shape, having two annular side walls joined by a plurality of axially oriented blades spaced about an inner periphery of the side walls. The housing includes a side inlet, or opposing openings that form a double inlet, to allow ambient air to enter the housing. There, it is accelerated by the blades of the rotating impeller and is exhausted through an exhaust opening that is oriented at a right angle to the air inlet or inlets.

Centrifugal fans or blowers may be connected to the output shaft of an electric motor in different ways. In one configuration, an electric motor drives a shaft on which the impeller is mounted by a belt; often the impeller is mounted on the output shaft of the electric motor. In other embodiments, a brushless direct current (DC) motor may be used. In such embodiments, the stator component of the electric motor is attached to the housing and is surrounded by the rotor component, the latter of which may be attached to rotate a fan or blower impeller.

There remains a need to provide a compact fan, especially a centrifugal fan, that is powered by an electric motor. Preferably, such a fan should be configured to have a relatively narrow profile and eliminate the need for pulleys or belts to connect the fan impeller to the electric motor, which may add to the cost of the fan, as well as increase the size of the fan.

SUMMARY

In one embodiment, a fan may include a housing having an inlet opening and an exhaust opening, a support shaft fixed to and positioned within the housing, a motor having a stator fixed on the support shaft, a rotor rotatably mounted on the support shaft, and an impeller attached to the rotor, whereby energization of the motor causes the rotor to rotate the impeller relative to the support shaft to move ambient air into the housing through the inlet opening and out the exhaust opening.

In another embodiment, a fan may include a housing having an inlet opening and an exhaust opening, a support shaft positioned within the housing, a motor having a stator mounted on the support shaft, and a rotor rotatably mounted on the support shaft, and an impeller attached to the rotor, the impeller having opposing end plates connected by a plurality of fan blades, the impeller configured such that the stator and rotor are positioned between the end plates, whereby energization of the motor causes the rotor to rotate the impeller relative to the support shaft to move ambient air into the housing through the inlet opening and out the exhaust opening.

In yet another embodiment, a centrifugal fan may include a housing having an inlet opening and an exhaust opening, a support shaft non-rotatably attached to and positioned within the housing, an electric motor having a stator fixed on the support shaft and a rotor rotatably mounted on the support shaft, and an impeller attached to the rotor, the impeller having opposing end plates interconnected by a plurality of fan blades, the impeller configured such that the stator and rotor are positioned between the end plates, whereby energization of the motor causes the rotor to rotate the impeller relative to the support shaft to move ambient air into the housing through the inlet opening and out the exhaust opening.

In still another embodiment, a method for operating a fan may include providing a housing having an inlet opening and an exhaust opening, positioning a support shaft within the housing, and energizing a motor, having a stator fixed on the support shaft and a rotor rotatably mounted on the support shaft, to rotate an impeller attached to the rotor, whereby the rotor rotates the impeller relative to the support shaft to move ambient air into the housing through the inlet opening and out the exhaust opening.

Other objects and advantages of the disclosed fan with inverted electric motor will be apparent from the following description, the accompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of an embodiment of the disclosed fan with inverted electric motor, wherein the fan is in the form of a centrifugal fan;

FIG. 2 is a front elevational view of the fan, in section, taken at line 2-2 of FIG. 1;

FIGS. 3A and 3B are perspective views of the motor and support shaft of the fan of FIG. 1, in which FIG. 3B shows the motor and support shaft in quarter section;

FIG. 4 is a detail in section of the motor of FIGS. 3A and 3B; and

FIG. 5 is a detail, in section, of the motor and support shaft of FIGS. 3A and 3B.

DETAILED DESCRIPTION

As shown in FIGS. 1 and 2, an embodiment of the disclosed fan with inverted electric motor may take the form of a centrifugal fan or blower, generally designated 10, and include a housing, generally designated 12, having an inlet opening, which in an embodiment may be a double-inlet housing having opposing frustoconical inlet bells 14, 16. In an alternate embodiment, the housing 12 may have only a single inlet opening, and may include only a single one of the inlet bells 14 or 16. The housing 12 may be generally involute or scroll-shaped, and include an exit or exhaust opening 18 from the interior 20. In an embodiment, the housing 12 also may include opposing, triangularly shaped support brackets 22, 24 that brace horizontally extending mounting flanges 26, 28.

In an embodiment, the support brackets 22, 24 and mounting flanges 26, 28 may be attached directly to the housing side walls 30, 32 by fasteners, such as rivets or nut and bolt combinations, and/or by a suitable adhesive or by brazing or welding. Also in an embodiment, the inlet bells 14, 16 may be attached to the side walls 30, 32, respectively, by similar fasteners, or by adhesive, brazing, or welding. Inlet bells 14, 16 may extend inwardly toward the center of the interior 20 of the housing 12. Additionally, the housing side walls 30, 32 may include mounting flanges 26, 28 that may be attached to pairs of front and rear stiffener flanges 34, 36. The stiffener flanges 34, 36 may extend vertically as shown in FIGS. 1 and 2 (only stiffener 34 for side wall 30 is shown, it being understood that side wall 32 also may include a similarly positioned stiffener 34).

In an embodiment, the centrifugal fan 10 may include a motor 38, which in the embodiment shown may be an inverted electric motor. In an embodiment, the motor 38 may be a three-phase, alternating current (AC) induction motor having an external rotor. In another embodiment, the motor 38 may be a brushless direct current (DC) motor with an external rotor. The motor 38 may be mounted on a fixed support shaft 40 that is non-rotatably attached to and extends between the mounting flanges 26, 28 of the side walls 30, 32 within the housing 12. In an embodiment, the shaft 40 may extend through and between the inlet bells 14, 16.

In embodiments, the motor 38 may be centered between the side walls 30, 32 on the support shaft 40. As shown in FIGS. 3A and 3B, the support shaft 40 may include flats 42, 44 at opposite ends thereof shaped to engage the flat surfaces of the flanges 26, 28. The flats 42, 44 may include central openings 46, 48 therethrough to receive fasteners, such as nut and bolt combinations 50, 52 (see FIG. 2), that may secure the flats 42, 44 at the ends of the shaft 40 to the housing 12 at mounting flanges 26, 28.

In an embodiment, the motor 38 may include a stator 66, which may be mounted on the support shaft 40, and an external rotor 80. The rotor 80 may include a barrel, generally designated 54, rotatably attached to the support shaft 40. The barrel 54 may include a pair of opposing, disc-shaped end frames 56, 58 mounted on the support shaft 40. A side wall 60 may be attached to and interconnect the end frames 56, 58. In embodiments, the side wall 60 may be cylindrical, as shown in the figures, or may have another shape, such as a polygonal shape (e.g., octagonal), that is substantially uniform about the support shaft 40. The barrel 54 thus may be formed by the side wall 60 and end frames 56, 58, and defines an enclosed interior space 62. In an embodiment, the stator 66 and windings of the rotor 80 of the motor 38 may be positioned between the end frames 56, 58 in the interior space 62 of the barrel 54. The side wall 60 may include a rib 64 that is raised in a substantially radial direction and extends about a periphery of the side wall 60, and radially outward therefrom, at approximately a midpoint between the end frames 56, 58. In an embodiment, the end frames 56, 58 and side wall 60 may be imperforate to prevent dust and other contaminants from entering the interior space 62 of the barrel 54 to protect the stator 66 and rotor 80.

As shown in FIGS. 3B, 4, and 5, the stator 66 may be non-rotatably fixed on and extend about the support shaft 40, for example, by a press fit or other well-known means. In an embodiment, as shown in FIG. 5, the support shaft 40 may include a longitudinally (i.e., axially) extending keyway 68 that receives a key 70 that engages a key slot 72 to secure the stator 66 to the support shaft and prevent relative rotation thereof. In an embodiment, the support shaft 40 may extend through a center of a generally cylindrical stator 66, so that the stator is concentric with the support shaft.

As shown in FIGS. 4 and 5, the support shaft 40 may include a passage 74 that is shaped to receive a power cable 76 from a source of electric power 78, which in an embodiment may take the form of an inverter, such as an inverter that provides three-phase electric power in an embodiment in which motor 38 is a three-phase AC induction motor. The power cable 76 may be electrically connected to the stator 66 to provide electrical power to the stator.

The windings of the external rotor 80 may be attached to the inner surface 82 of the side wall 60 of the barrel 54. In an embodiment, the stator 66 and windings of the rotor 80 may be completely enclosed within the barrel 54. The end frames 56, 58 of the barrel 54 may include collars 84, 86 that may be attached to central openings 88, 90, respectively, in the end frames and secured thereto by screws 92. The collars 84, 86 may be shaped to receive bearings, such as ball bearing sets 94, 96, that may be pressed onto, or otherwise secured to, the support shaft 40. The bearing sets 94, 96 may allow the barrel 54 and rotor 80 to rotate relative to the support shaft 40 and the stator 66. In an embodiment, the barrel 54 may be concentric with the support shaft 40. In an embodiment, the barrel 54 may be centered between the side walls 30, 32 on the shaft 40.

As shown in FIGS. 1 and 2, an impeller or fan wheel, generally designated 100, may be completely enclosed within the housing 12 (i.e., no part of the impeller 100 protrudes from the housing 12) and attached to the barrel 54 of the motor 38. The impeller 100 may be configured such that the stator 66, rotor 80, and barrel 54 of the motor 38 are enclosed within the impeller (i.e., no part of the motor 38 protrudes from the impeller 100). The impeller 100 may include opposing end plates 102, 103 that may be annular in shape and include central openings 104, 105. In an embodiment, the impeller 100 may be positioned between the inlet bells 14, 16.

The opposing inlet bells 14, 16 may communicate with the impeller 100, and in an embodiment, the central openings 104, 105 of the end plates 102, 103 each communicate with an adjacent one of the inlet bells 14, 16 such that inlet air is directed through the inlet bells to an interior of the impeller. In an embodiment, the central openings 104, 105 of the end plates 104, 105 may be positioned adjacent, and are shaped to receive, the inner ends 106, 108 of the inlet bells 14, 16 of the housing 12. In an embodiment in which the housing 12 includes only a single inlet and only a single one of the inlet bells 14 or 16, the impeller 100 may include only a single one of the central openings 104 or 105 in an associated one of the end plates 102, 103 in communication with the single inlet bell.

The impeller 100 may include an annular support disc 110 that may be positioned between the end plates 102, 103. The annular support disc 110 may be attached to the raised rib 64 of the side wall 60 of the barrel 54 so that the impeller is mounted on the raised rib of the barrel 54. In embodiments, the connection between the annular disc 110 and rib 64 may be effected by fasteners, such as screws or nut and bolt combinations, by welding or brazing, or by a suitable adhesive. In embodiments, the annular support disc 110 may be supported for rotation about the shaft 40 solely by the connection to the rib 64 of the barrel 54.

A plurality of blades, which in embodiments may be airfoil-shaped blades 112, may be attached to and extend between the end plates 102, 103 and the annular support disc 110. In FIG. 1, the blades are shown as backward-curved airfoil-shaped blades 112. In embodiments, the impeller 100 may include forward curved blades or straight radial blades. In an embodiment, a first plurality of the blades 112 may be attached to and extends between a first one 102 of the pair of end plates 102, 103 and the annular support disc 110, and a second plurality of the blades may be attached to and extend between a second one 103 of the pair of end plates and the annular support disc. In an embodiment, the annular support disc 110 may be positioned at approximately a midpoint of the impeller 100, so that when attached to the raised rib, the impeller may be centered relative to the barrel 54 and motor 38 along the support shaft 40.

In operation, the motor 38 may receive electrical power from the inverter 78 (FIG. 4) or another power source, such as three-phase electrical power or other power, through cable 76, thereby energizing the motor 38, in an embodiment specifically the stator 66. Energizing the stator 66 may cause the rotor 80 to rotate, thereby rotating the barrel 54, and impeller 100 mounted on it, counterclockwise in the direction of arrow A in FIG. 1 about the fixed stator 66 and support shaft 40.

The orientation and movement of the blades 112 with the rotation of the impeller 100 may cause ambient air to be drawn inwardly through the inlet bells 14, 16, to the interior of the impeller 100. The air in the interior of the impeller 100 is guided radially outwardly from the impeller by the blades 112, which may cause air pressure to build up within the interior 20 of the housing 12 about the impeller, causing air to be expelled from the housing through exit 18 in the direction of arrows B. The stator 66 and rotor 80 of the motor 38 may be sealed from dust and other contaminants that may be present in the air within the interior 20 of the housing by the barrel 54, in an embodiment wherein the end frames 56, 58 and side wall 60 of the barrel are imperforate, because the stator 66 and windings of the rotor 80 are enclosed by the barrel.

An advantage of the disclosed fan 10 is that the external rotor 80 of the motor 38 may be integral with the impeller 100, so that the barrel 54 of the rotor may be attached directly to the impeller (i.e., without intermediary components). This arrangement may eliminate the need to provide pulleys and other drive mechanisms to connect a motor to a blower wheel that increase cost and require additional space. The support shaft 40 may be integral with the stator 66 of the motor 38, supporting the motor 38 within the housing 12, holding the stator fixed, and at the same time connecting the stator and the motor to a fixed support 22, 24 of the housing 12. Further, the symmetrical design of the fan 10 (relative to a vertical centerline in FIG. 2) may minimize bending moments that may be transmitted through the bearings 94, 96 (see FIG. 4) and may prolong bearing life.

While the form of apparatus and method disclosed herein constitute preferred embodiments of the fan with inverted electric motor, it is to be understood that the invention is not limited to this precise apparatus and method, and that changes may be made therein without departing from the scope of the invention. 

What is claimed is:
 1. A fan comprising: a housing having an inlet opening and an exhaust opening; a support shaft fixed to and positioned within the housing; a motor having a stator fixed on the support shaft, and a rotor rotatably mounted on the support shaft; and an impeller attached to the rotor, whereby energization of the motor causes the rotor to rotate the impeller relative to the support shaft to move ambient air into the housing through the inlet opening and out the exhaust opening.
 2. The fan of claim 1, wherein the impeller is enclosed within the housing.
 3. The fan of claim 1, wherein the motor is enclosed within the impeller.
 4. The fan of claim 3, wherein the housing is a double-inlet housing.
 5. The fan of claim 4, wherein the housing includes an inlet selected from a single inlet bell communicating with the impeller, and opposing inlet bells communicating with the impeller.
 6. The fan of claim 5, wherein the impeller includes at least one central opening shaped to receive an inner end of at least one of the inlet bells.
 7. The fan of claim 1, wherein the rotor includes a barrel rotatably attached to the support shaft; and the impeller is attached to the barrel to rotate with the barrel.
 8. The fan of claim 7, wherein the stator and rotor are enclosed within the barrel.
 9. The fan of claim 8, wherein the barrel includes opposing end frames rotatably mounted on the support shaft and a side wall attached to and extending between the end frames; and wherein the impeller is attached to the side wall of the barrel.
 10. The fan of claim 9, wherein the barrel is positioned within the impeller.
 11. The fan of claim 1, wherein the support shaft is non-rotatably attached to the housing.
 12. A fan comprising: a housing having an inlet opening and an exhaust opening; a support shaft positioned within the housing; a motor having a stator mounted on the support shaft, and a rotor rotatably mounted on the shaft; and an impeller attached to the rotor, the impeller having opposing end plates connected by a plurality of fan blades, the impeller configured such that the stator and rotor are positioned between the end plates; whereby energization of the motor causes the rotor to rotate the impeller relative to the support shaft to move ambient air into the housing through the inlet opening and out the exhaust opening.
 13. The fan of claim 12, wherein the rotor includes a barrel, and the impeller is mounted on the barrel.
 14. The fan of claim 13, wherein the barrel includes a raised rib, and the impeller is mounted on the raised rib.
 15. The fan of claim 14, wherein the barrel includes a pair of opposing end frames mounted on the support shaft, and a side wall attached to and interconnecting the end frames; and wherein the motor is positioned between the end frames.
 16. The fan of claim 14, wherein the impeller includes an annular support disc positioned between the end plates and attached to the blades; wherein the annular support disc is attached to the raised rib of the barrel.
 17. The fan of claim 14, wherein a first plurality of the blades are attached to and extend between a first one of the pair of end plates and the annular support disc; and a second plurality of the blades extend between a second one of the pair of end plates and the annular support disc.
 18. The fan of claim 12, wherein the inlet opening of the housing includes opposing inlet bells; the impeller is positioned between the inlet bells; and the end plates of the impeller each include a central opening communicating with an adjacent one of the inlet bells.
 19. A centrifugal fan comprising: a housing having an inlet opening and an exhaust opening; a support shaft non-rotatably attached to the housing and positioned within the housing; an electric motor having a stator fixed on the support shaft, and having a rotor rotatably mounted on the support shaft; and an impeller attached to the rotor, the impeller having opposing end plates interconnected by a plurality of fan blades, the impeller configured such that the stator and rotor are positioned between the end plates; whereby energization of the motor causes the rotor to rotate the impeller relative to the support shaft to move ambient air into the housing through the inlet opening and out the exhaust opening.
 20. The centrifugal fan of claim 19, wherein the electric motor is selected from an inverted alternating current motor, and an inverted brushless direct current motor.
 21. A method operating a fan, the method comprising: providing a housing having an inlet opening and an exhaust opening; positioning a support shaft within the housing; and energizing a motor, having a stator fixed on the support shaft and a rotor rotatably mounted on the support shaft, to rotate an impeller attached to the rotor, whereby the rotor rotates the impeller relative to the support shaft to move ambient air into the housing through the inlet opening and out the exhaust opening. 